Shaped marble products are used widely for a variety of purposes, such as plumbing products which include sinks, toilets, bathtubs, shower stall bases and the like; decorative moldings; wall panels; and shelving systems to name only a few. To form these products out of solid marble is usually expensive and unsanitary. Cast marble products have become a viable substitute for natural marble where the desired article may be formed by casting and setting a marble-like composition in a mold. By casting the product, greater flexibility in design is permitted and the surfaces are finished in a manner which provides sanitary surfaces. Commonly, various types of granulates especially of calcium carbonate admixed with an appropriate setting resin have been used in forming molded products particularly in the plumbing industry. The problem, however, in casting marblelike compositions to form these products is that the resultant product is very heavy. For example, a bathtub formed in this manner may weigh in excess of 500 pounds, therefore, resulting in difficult installation procedures.
In an attempt to reduce the weight of the cast marble product, attempts have been made to incorporate in the marble product various types of glass spheres. However, the glass spheres tend to break up or dissolve during mixing of the mineral filler such as calcium carbonate with the resin. Hence there is very little reduction in weight of the product and furthermore the product tends to lose structural strength due to the break-up of the glass spheres.
According to this invention, a filler composition has been developed which results in a cast marble product weighing considerably less than existing types of cast marble products, yet maintaining desired structural characteristics.